Don't let isPermImmMask handle v16i32 since VPERMI doesn't match on that type. Remove 128-bit vector handling from isPermImmMask too, it's covered by isPSHUFDMask.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188449 91177308-0d34-0410-b5e6-96231b3b80d8